Unix timestamp converter: how Unix time works
A Unix timestamp is the number of seconds that have passed since 1 January 1970 00:00:00 UTC (the Unix epoch). Developers store this number instead of a date because it is unambiguous across time zones and easy to compare.
Why timestamps not dates?
A string like '25/09/2026' is ambiguous — is it September 25th or 25th of September? A timestamp has no time zone, no format and no locale, so it travels between servers and languages without misinterpretation. Databases, JWT tokens and API logs all use them.
Convert with FreetoolsY
Paste a Unix timestamp into the Unix Timestamp Converter. It reads seconds, milliseconds and microseconds, shows the UTC time and your local time, and includes a copy-friendly ISO string for logs and tests.
- Convert back and forth: date to timestamp works too.
- Check whether the source used seconds (10 digits) or milliseconds (13 digits).
- Use the 'now' button to capture the current moment exactly.
Common mistakes
The most frequent bug is a missing zero: multiplying seconds by 1000 in JavaScript (or dividing by 1000 in other languages) turns a valid timestamp into a far-future or far-past date. The Date Difference tool helps verify the span between two such moments.